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onsemi BF421ZL1G
- Part No.:
- BF421ZL1G
- Manufacturer:
- onsemi
- Category:
- Single Bipolar Transistors
- Package:
- TO-226-3, TO-92-3 Long Body, Formed Leads
- Datasheet:
-
BF421ZL1G.pdf
- Description:
- TRANS PNP 300V 0.05A TO92
- Quantity:
- Payment:
- Shipping:
Inventory:8,260
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Product details
Overview
BF421ZL1G from onsemi is a PNP silicon high-voltage transistor rated for −300 VCEO, −300 VCBO, and −5.0 VEBO, with continuous collector current of −500 mA and DC current gain (hFE) ≥50 at −25 mA/−20 V. It operates across −55°C to +150°C and is used in high-voltage switching, relay drivers, and industrial power control circuits.
For engineers reviewing the BF421ZL1G datasheet, pinout, applications, or equivalent options, key selection considerations include its −300 V breakdown rating, TO-92 package thermal resistance (RJA = 150°C/W), saturation voltage (VCE(sat) ≤ −0.5 V at −20 mA/−2.0 mA), and fT = 60 MHz small-signal bandwidth.
Technical Context
This PNP bipolar junction transistor is optimized for high-voltage linear and switching operation in industrial and power management systems. Its design supports stable gain over temperature (hFE maintained from −55°C to +125°C) and low leakage (ICBO ≤ −0.01 A, IEBO ≤ −100 nA).
The device features a TO-92 package with defined lead assignments (Pin 1 = Emitter, Pin 2 = Collector, Pin 3 = Base) and thermal performance validated on FR4 board with 200 mm² copper (RJL = 68°C/W). Its fT and Cre = 2.8 pF support moderate-frequency amplification and switching up to 20 MHz.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCEO | −300 V - Supports circuit operation up to 300 V reverse bias between collector and emitter without breakdown. |
| hFE | ≥50 at −25 mA/−20 V - Ensures sufficient current amplification for driver-stage gain in high-side switch configurations. |
| VCE(sat) | ≤ −0.5 V at −20 mA/−2.0 mA - Minimizes conduction loss and heat generation in saturated switching applications. |
| fT | 60 MHz - Enables use in audio-frequency amplifiers and medium-speed switching (e.g., PWM at ≤1–2 MHz with margin). |
| RJA | 150°C/W - Requires careful PCB copper area planning (200 mm² 1 oz Cu per datasheet test condition) for thermal management. |
| TJ Range | −55°C to +150°C - Qualified for extended industrial and under-hood automotive environments without derating below −55°C. |
Pinout & Package
BF421ZL1G is housed in a Pb-free TO-92 (Case 29, Style 14) package with straight leads in ammo pack configuration. The package dimensions conform to ON Semiconductor's CASE 029−11 specification, with standardized lead pitch and seating plane geometry for manual and automated through-hole assembly.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Emitter) | Current source terminal for PNP operation | Connected to higher potential rail in high-side switch topologies; must handle full load current path. |
| 2 (Collector) | Current sink terminal | Biasing node for high-voltage loads; withstands −300 V relative to emitter under open-base conditions. |
| 3 (Base) | Control input for minority-carrier injection | Requires current-limited drive (e.g., series resistor) to achieve target IC/IB = 10 for saturation. |
Key Features
| Feature | Design Value |
|---|---|
| High-voltage blocking capability | Rated for −300 VCEO and −300 VCBO, enabling direct interface with 240 VAC rectified rails or flyback snubbers. |
| Low saturation voltage | VCE(sat) ≤ −0.5 V ensures <0.01 W conduction loss at −20 mA, reducing thermal stress in compact layouts. |
| Wide operating temperature range | Specified from −55°C to +150°C junction temperature, supporting deployment in unheated enclosures or near power stages. |
| Pb-free, RoHS-compliant construction | Meets EU RoHS Directive 2011/65/EU and halogen-free/BFR-free requirements for environmentally regulated end equipment. |
Applications
| Industrial Relay Drivers | High-Voltage Power Supply Control |
|---|---|
Use Scenario: Driving electromagnetic relays with coil voltages up to 250 VDC in programmable logic controllers and factory automation I/O modules. IC Role / Device Role / Timing Role: High-side PNP switch controlling relay coil current path to ground, with base driven by microcontroller GPIO via current-limiting resistor. Use Value: −300 VCEO rating prevents breakdown during relay coil flyback transients; VCE(sat) ≤ −0.5 V limits self-heating during sustained activation. | Use Scenario: Regulating auxiliary bias supplies in offline AC/DC converters where primary-side sensing requires high-voltage transistor isolation. IC Role / Device Role / Timing Role: Linear pass element or feedback switch in high-side error amplifier stage, referenced to rectified bulk voltage. Use Value: Stable hFE across temperature ensures consistent loop gain; RJA = 150°C/W allows thermal design with minimal copper area. |
| Capacitor Discharge Circuits | Ignition System Drivers |
Use Scenario: Rapidly discharging high-energy storage capacitors (e.g., flash lamps, pulse lasers) in medical and industrial equipment. IC Role / Device Role / Timing Role: Main discharge switch placed between capacitor positive terminal and ground, triggered by low-voltage logic signal. Use Value: −300 VCBO withstands full capacitor voltage pre-discharge; fT = 60 MHz supports fast turn-on (<100 ns) with proper base drive. | Use Scenario: Controlling primary current in inductive ignition coils for small engines and industrial burners. IC Role / Device Role / Timing Role: Ground-referenced switch interrupting coil primary current to induce high-voltage secondary spark. Use Value: Safe Operating Area (SOA) supports repetitive 10 ms pulses at >100 mA; −55°C to +150°C rating accommodates engine bay thermal cycling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar PNP high-voltage transistor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BF423ZL1G | VCEO = −250 V (50 V lower), otherwise identical package, pinout, and hFE spec. | Suitable where system max voltage is ≤250 V; not recommended for 300 V designs. | Select BF423ZL1G only if voltage margin allows reduction; no layout change needed. |
| MPSA92 | VCEO = −300 V, but hFE min = 25 (vs. 50), RJA = 200°C/W (vs. 150°C/W), TO-92 same. | Acceptable for less demanding gain/stability requirements; requires larger copper area for thermal management. | Use MPSA92 only when gain and thermal headroom are relaxed; verify SOA under actual load conditions. |
Compared with BF421ZL1G, BF423ZL1G offers identical form-factor and drive compatibility but reduced voltage margin, while MPSA92 trades gain and thermal efficiency for broader legacy availability-neither is a drop-in replacement without validation.
Availability
BF421ZL1G is available at Aetrix Electronics and suitable for industrial relay drivers, high-voltage power supply control, and capacitor discharge circuits requiring stable component supply and long-term manufacturability.
Supply support for BF421ZL1G includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
onsemi (formerly ON Semiconductor) is a global semiconductor supplier focused on energy-efficient electronics, delivering power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and IoT applications.
The BF421ZL1G belongs to onsemi's high-voltage bipolar transistor product line, engineered specifically for robust switching and linear operation in industrial power interfaces where reliability under voltage stress and thermal cycling is critical.
FAQ
What is the maximum collector-emitter voltage rating for BF421ZL1G?
The BF421ZL1G has a guaranteed minimum collector-emitter breakdown voltage (V(BR)CEO) of −300 Vdc at IC = −1.0 mAdc and IB = 0. This rating applies under DC or pulsed conditions within the device's Safe Operating Area and is validated per onsemi's BF421/D datasheet Rev. 5. Designers must ensure operating VCE remains below this value with appropriate safety margin.
Is BF421ZL1G compatible with standard TO-92 footprints?
Yes, BF421ZL1G uses the industry-standard TO-92 package (Case 29, Style 14) with pin 1 = Emitter, pin 2 = Collector, pin 3 = Base. Its mechanical dimensions-including lead pitch, body height, and seating plane-match JEDEC TO-92 specifications, ensuring compatibility with existing through-hole PCB footprints and assembly tooling designed for TO-92 devices.
What is the DC current gain (hFE) of BF421ZL1G under typical operating conditions?
The BF421ZL1G guarantees hFE ≥ 50 when tested at IC = −25 mAdc and VCE = −20 Vdc at TA = 25°C. Gain remains functional across the full −55°C to +150°C junction temperature range, as shown in Figure 1 of the BF421/D datasheet, making BF421ZL1G suitable for temperature-stable amplifier and driver stages.
Does BF421ZL1G meet RoHS and halogen-free requirements?
Yes, BF421ZL1G is explicitly marked Pb-free, halogen-free/BFR-free, and RoHS compliant per the onsemi BF421/D datasheet. It satisfies EU Directive 2011/65/EU and carries the "Pb-Free Package" designation in its ordering information and marking diagram, confirming compliance for environmentally regulated end equipment.
Can BF421ZL1G be used in switching applications above 1 MHz?
While BF421ZL1G has an fT of 60 MHz, its practical switching speed is limited by stored charge and saturation recovery time. For clean hard-switching above 1 MHz, external base clamping or Baker clamp techniques are required. The BF421ZL1G is best suited for ≤500 kHz switching or linear amplification; consult Figures 2–4 in the BF421/D datasheet for dynamic performance curves.
BF421ZL1G Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-226-3, TO-92-3 Long Body, Formed Leads
- Packaging:
- Tape & Box (TB)
- Product Status:
- Obsolete
- Transistor Type:
- PNP
- Current - Collector (Ic) (Max):
- 50 mA
- Voltage - Collector Emitter Breakdown (Max):
- 300 V
- Vce Saturation (Max) @ Ib, Ic:
- 500mV @ 2mA, 20mA
- Current - Collector Cutoff (Max):
- 10nA (ICBO)
- DC Current Gain (hFE) (Min) @ Ic, Vce:
- 50 @ 25mA, 20V
- Power - Max:
- 830 mW
- Frequency - Transition:
- 60MHz
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-92 (TO-226)
BF421ZL1G FAQ
1.How can I place an order for BF421ZL1G through Aetrix?
Please submit a Request for Quotation (RFQ) for BF421ZL1G on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for BF421ZL1G reliable?
The price and inventory of BF421ZL1G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BF421ZL1G is usually 5 days.
3.What payment methods are accepted for BF421ZL1G?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BF421ZL1G transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BF421ZL1G?
BF421ZL1G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BF421ZL1G order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for BF421ZL1G?
For technical support, including BF421ZL1G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BF421ZL1G requirements.
6.How does Aetrix verify that BF421ZL1G is sourced from the original manufacturer or authorized distributors?
All BF421ZL1G products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that BF421ZL1G meets industry standards.
7.What is the process for return or replacement of BF421ZL1G?
All BF421ZL1G units undergo pre-shipment inspection (PSI). If there is an issue with BF421ZL1G, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The BF421ZL1G part is unused and in its original packaging.
Return procedure for BF421ZL1G:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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